1. Field of the Invention
The present invention relates to a toner for developing an electrostatic charge image by an image forming method such as electrophotography or electrostatic printing, or a toner for a toner-jet system. In addition, the present invention relates to a method of producing the toner.
2. Description of the Related Art
An image forming method involving visualizing an electrical or magnetic latent image on a recording medium by using toner is employed for developing the latent image. A representative example of the image forming method is an electrophotographic method. The electrophotographic method involves: electrically forming a latent image on a photosensitive member by using various means; developing the latent image with toner to form a toner image; transferring the toner image onto a transfer material such as paper as required; and fixing the toner image to the transfer material by employing a fixing means such as heating, pressurization, pressurization under heat, or solvent steam to provide an image.
A heat roller fixing method or a film fixing method involves causing a heat roller or a fixation film to pass a toner image on a sheet to be fixed while contacting the heat roller or the fixation film with the toner image to perform fixation. In each of the fixing methods, the surface of the heat roller or of the fixation film and toner on the sheet to be fixed are brought into contact with each other, hence thermal efficiency in melt-attaching the toner to the sheet to be fixed is extremely good. Accordingly, the fixing methods enable fixation to be performed quickly, and are extremely useful in an electrophotographic device. However, in each of the above fixing methods, the surface of the heat roller or of the fixation film contacts with the toner in a molten state, so that part of the toner adheres to the surface of the heat roller or of the fixation film. As a result, an offset phenomenon in which the toner adhering to the surface of the heat roller or of the fixation film transfers to the next sheet to be fixed again occurs, and the sheet to be fixed is contaminated in some cases.
An additional improvement in toner performance such as fixability or offset resistance is needed for coping with recent demands on an electrophotographic device, such as reductions in size and weight, energy saving, and an improvement in reliability.
A toner has been disclosed in which a rate of change in flow tester viscosity of the toner is specified (see Japanese Patent Application Laid-Open No. S63-58356). In addition, a toner has been disclosed in which the absolute value of the gradient of the graph of a resin mixture is specified (see Japanese Patent Application Laid-Open No. H08-334926). However, a toner has been desired which has better low-temperature fixability, higher gloss and a wider fixable temperature region, and is more excellent in durability, as compared with the toners disclosed in Japanese Patent Application Laid-Open No. S63-58356 and Japanese Patent Application Laid-Open No. H08-334926 mentioned above.